Fuel cells have been proposed as a power source for electric vehicles and other applications. In proton exchange membrane (PEM) type fuel cells, hydrogen is supplied to an anode of the fuel cell and oxygen is supplied as an oxidant to a cathode. Large amounts of hydrogen are required to power the fuel cells of fuel cell powered vehicles. Typically, large quantities of hydrogen are stored at ambient temperature and at up to 70 MPa in high-pressure storage tanks disposed on an undercarriage of the vehicle.
To fill the storage tank with hydrogen and to extract hydrogen from the tank, inlet and outlet conduits adapted to facilitate fluid flow are disposed through a sidewall of the storage tank. The conduits are typically disposed through the sidewall with a portion inside the tank and a portion exposed to ambient air. A seal is typically disposed between the conduits and the sidewall to militate against leakage of fluid therebetween and heat transfer to the fluid being stored inside of the storage tank.
In a typical high-pressure storage tank, an amount of heat will enter the tank upon compression of the hydrogen in the tank during a tank filling operation. Similarly, the temperature of the hydrogen and the tank will decrease as the hydrogen is extracted from the tank. During tank filling and immediately thereafter, the hydrogen in the tank is at an elevated temperature. At a time after filling and during regular operation of the vehicle, the hydrogen in the tank is at ambient temperature. During extraction, the hydrogen can cool to as low as −80° C. At temperatures substantially lower than −40° C., the seal between the sidewall of the storage tank and the conduits can fail, allowing leakage of hydrogen to the environment. Therefore, as the hydrogen is extracted at a temperature colder than −40° C., the seal may be damaged allowing hydrogen leakage. Accordingly, there is a need for an improved high-pressure storage tank, and more particularly, a storage tank that minimizes damage to the seal.
It would be desirable to develop a high-pressure storage tank with a means for internally heating a fluid in the tank during an extraction thereof from the storage tank operation to militate against damage to a seal.